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  <title>Document</title>
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  <script>
    // 两数之和求下标
    const arr = [3,6,9,8], target = 15

    let newArr = []
    for(let i = 0;i < arr.length; i++) {
      for(let j = i + 1; j < arr.length; j++) {
        if(arr[i] + arr[j] === target) {
          newArr = [i,j]
        }
      }
    }
    console.log(newArr);
  </script>
</body>
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